docs: def from_statement(cls, statement):
          """ Create a selection function from a statement """
          if statement[0] in ["TS", "TIMESTAMP", "UTCTIMESTAMP", "UTCTS"]:
              return TimestampFunction.from_statement(statement)
          elif statement[0] in ["NOW", "UTCNOW"]:
              return NowFunction.from_statement(statement)
          else:
              raise SyntaxError("Unknown function %r" % statement[0])